Interconnecting device for movable contacts of keyboard switches

ABSTRACT

An interconnecting device for movable contacts of multistage keyboard switches in an electronic musical instrument in which a printed circuit board structure capable of interconnecting the movable contacts as groups in place of the conventional individual wirings is used. The device simplifies the complicated wiring operations in manufacture and also troublesome, complex connections in the movable contacts, resulting in elimination of cross-talking due to the existence of stray capacitances caused by unreliable connections.

United States Patent Murakami May 16, 1972 [s41 INTERCONNECTING DEVICE FOR 3,313,986 4/1967 Kilby ...317/101 cw MOVABLE CONTACTS OF KEYBOARD 3,454,91 l 7/1969 Rouzier et al ..335/3 12 SWITCHES OTHER PUBLICATIONS [721 Mmkam" HamamaSU' Japan Foldable Printed Circuits, Technograph Printed Circuits [73] Assignee: Nippon Gakki Seizo Kabushiki Kaisha, g pp- Hamamatsu-shi, Japan Flexprint Wiring Handbook of Design information" San- F d J y 22 1970 ders Associates, Inc. Nashua, NH, p. l and p. 14.

2 APPL 57,077 Primary Examiner--David Smith,Jr.

Attorney-Cushman, Darby & Cushman [30] Foreign Application Priority Data [57] ABSTRACT July 26, 1969 Japan ..44/70962 An interconnecting device for movable contacts ofmumsmge keyboard switches in an electronic musical instrument in 84/424 which a printed circuit board structure capable of intercon- I acting the movable contacts as groups in place Ofthe convem [58] new of Search "317/101 tional individual wirings is used. The device simplifies the complicated wiring operations in manufacture and also References Cited troublesome, complex connections in the movable contacts,

resulting in elimination of cross-talking due to the existence of UNITED STATES PATENTS stray capacitances caused by unreliable connections. 3,384,956 5/1968 Flanders et al. ..3l7/l01 CW 3Claims,7DrawingFigures V a at 1? F; F; E: 03 a C: c; B2 A2 A: G2 G: F: F: E: 0: D2 c; 1c: 4\

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*1 1 I I I r I 1 I x 6b, 7b 7o, 8 9 ll IO 5c 20 5 6b 6a PATENTEDMAY 16 I972 SHEET 2 [1F 3 INTERCONNECTING DEVICE FOR MOVABLE CONTACTS OF KEYBOARD SWITCHES The present invention relates to connectors for use in a keyboard switches assembly, and more particularly, to an interconnecting device for movable contacts of multistage keyboard switches in an electronic musical instrument.

It is an object of the present invention to provide an interconnecting device (intramanual coupler) to obtain highly simplified but unfailing electric interconnection of the movable contacts of the multistage keyboard switches.

Another object of the present invention is to provide an interconnecting device to insure operational reliability of the electronic musical instrument and to insure freedom of this instrument from cross-talking.

vA further object of the present invention is to provide an interconnecting device simple in construction and easy to manufacture and low in cost. I Other objects, features, and advantages of the present invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of an embodiment of the interconnecting device of the present invention for movable contacts of pre-arranged multistage keyboard switches;

FIG. 2 is cross sectional view, on an enlarged scale, taken along the line 11-11 in FIG. I; FIG. 3 is a cross sectional view, on an along the line III-[11in FIG. 1;

FIG. 4 is a front view of the interconnecting device of FIG. I mounted on some of the terminal members of the movable contacts projecting from the rear side of the keyboard switches; I

FIG. 5 is across sectional view, on an enlarged scale, taken along the line V-V in FIG. 4;

FIG. 6 is an explanatory representation, showing the electric connections in a conventional keyboard switch assembly; and v I FIG. 7 is a front view of the interconnecting body showing another embodiment of the present invention.

Like reference numerals and symbols in the drawings indicate like parts.

, Prior to describing preferred embodiments of the present enlarged scale, taken invention, description is made on a conventional keyboard switch assembly for electronic musical instruments by referring to FIG. 6. p

Many of the conventional keyboard switch assemblies for electronic musical instruments are comprised in the form of multistage switches as shown in FIG. 6 such that each of a predetermined number of, playing keys which are indicated generally by the reference numeral 101 and which may be arranged in rows of key note names, for example, C,, C: C

. C C, C, is provided with a plurality of switches, for example, three switches 102, 103 and 104, all of which are adapted to be either closed or opened simultaneously by actuating any single key. In such an arrangement, the switches generally indicated by 103 which are contained in the intermediate stage are those for keying the respective tone signals C (65 Hz) C C C C (1,047 Hz) of8-footregister notes (notes having pitches same as the key note names). The switches generally indicated by 102 which are contained in the uppermost stage represent those for keying the respective tone signals C (131 Hz) C C C C (2,093 Hz) of 4-foot register notes (notes having pitche one octave higher than the key note names). The switches generally indicated by 104 which are contained in the lowermost stage represent those for keying the respective tone signalsC (33I-Iz)...C,...C,...C,...C,(523I-Iz)ofl6- foot register notes (notes having pitches one octave lower than the key note names). Each switch comprises a movable contact and a stationary contact. Movable contacts are provided individually so as to correspond to the respective switches whereas the stationary contacts are provided in the form of busbars and in common for each stage. The stationary contacts for each stage are connected, at one terminal thereof, to one common output line among thethree separate output lines 1,, 1, and 1 These respective common output lines, in turn, are connected to circuits such as tone coloring circuits A,, A, and A respectively. Thereafter, via tone volume controls B B and B respectively, the output terminals of the volume controls are connected in common and this common line is connected to an amplifier G and a loud speaker S successively.

On the other hand, wiring is arranged among the movable contacts so that the movable contacts for providing the same pitch tone signals contained in the different stages of the switches are connected with each other. Along with this, wiring is provided between the tone source circuits and the terminals of the respective movable contacts of the 16-foot notes (C, C contained in the lowermost stage and the terminals of the respective movable contacts of the notes of those 8-foot register and 4-foot register not contained in the 16-foot register (i.e., CI, C in the 8-foot register, and C C, in the 4-foot register) to provide such tone signals as will correspond to the respective tone pitches.

In the foregoing construction of the keyboard switches of the prior art, a key corresponding to, for example, C, may be depressed. whereupon, the switch in 4-foot register for C tone signal, the switch in 8-foot register for C tone signal and the switch in 16-foot register for C tone signal are closed simultaneously. As a consequence, tone signals having pitches of C C and C are supplied to the common output lines 1,, l and 1 respectively. These tone signals are then passed through the respective tone coloring circuits and supplied to the tone volume controls 8,, B and B respectively, in which the input tone signals are selected into a single tone or a composite tone. Thereafter, the outputs of the tone volume controls are amplified by the amplifier G and are radiated from the loudspeaker S as acoustic musical sounds.

It is to be noted that the connections between the terminals of those movable contacts in an upper stage of a multi-stage keyboard switch assembly and the terminals of those movable contacts in the adjacent lower stage which both represent the same tone pitches, have been performed in the past by the use of lead wires separately for each connection. Therefore, wiring operations not only encountered a great deal of difficulty but also frequently led to erroneous connections because of the fact that wiring had to be effected between a great number of movable contact terminals of a similar shape in a limited confined space of the keyboard switch assembly.

In order to obviate the abovementioned drawbacks of the prior art, the present invetion contemplates the provision of a connector structure comprising an insulated base plate equipped with a printed circuit thereon and being capable of establishing simultaneous connections between the terminals of a plurality of selected movable contact in one stage and the terminals of the same number of selected movable contacts located in the next stage and representing the same tone pitches.

Description of the present invention will hereunder be made on an embodiment by referring to the accompanying drawings.

As is best seen in FIGS. 4 and 5, reference numeral 1 represents a switch box. Numeral 2 generally represents movable contact arms which are arranged in multiple stages and located in such positions as will correspond to the playing keys (not shown). Each of these movable contact arms 2 has a terminal strip 2a which projects beyond the rear surface of the switch box 1. The respective projecting terminal strips 2a are arranged so that those located in the uppermost stage correspond to tone signals of 4-foot notes, that those in the intermediate stage correspond to tone signals of 8-foot notes and that those in the lowermost stage correspond to tone signals of l6-foot notes. Below the foremost end of each movable contact arm in the aforesaid multistage arrangement is provided a rod having a good conductivity. In this embodiment these conductive rods are in the form of busbars and they are supported on the opposite side panels of the switch box 1 to provide common stationary contact rods 3 for each stage. On the other hand, the actuator portion 4 of each playing key is passed vertically through the switch box 1. These actuator portions 4 and the respective movable contact arms 2 are arranged that they may be brought into engagement with each other in such a way that, when a key is depressed, the respective movable contact arms 2 relating to this particular key will close the circuits simultaneously and that, conversely, when this depression is removed, they open the circuits at the same time. It should be understood that the playing keys are arranged in a side-by-side row of C C C C C C as shown in part in FIG. 4.

Referring to FIG. 1, numeral 5 represents a base plate which constitutes the connector device for interconnecting the terminals of a plurality of movable contact arms of selected two groups, e.g. a group of C C keys and a group of C C' keys shown in FIG. 4. This base plate 5 is formed with an insulated material such as a Mylar film. The base plate 5 has a length which is slightly greater than the distance between the extreme outer terminal strips in which are disposed 14 of them. The breadth of the base plate 5 is somewhat greater than the distance between the terminal strips of the uppermost and the lowermost stages. The longitudinal upper and lower bilateral edges of the base plate 5 are prepared each in an L- shape by a vertical cutout. More specifically, an upwardly protruding lug portion 5a extends from the upper longitudinal edge of the base plate 5 on the extreme right side to form a shoulder thereat, and a downwardly protruding lug portion 5b extends from the lower longitudinal edge on the extreme left side, forming a similar shoulder.

Thus, the base plate 5 has a longitudinal portion having a reduced breadth between these two opposite lug portions 5a and 5b. An elongated slit 50 having opposite vertical end faces is formed through the base plate 5 so as to lie in the central region longitudinally thereof. The vertical end face line of this elongated slit 5c on the extreme right side lies aligned with the vertical inner end face line of the shoulder which is formed by vertically cutting out a part of the base plate to leave the righthand lug portion 5a. Similarly, the vertical end face line of the elongated slit SC on the extreme left side is positioned to be aligned with the vertical inner end face line of the vertically cutout shoulder of the left lug portion 5b. This elongated slit 50 has a length sufficient for the passage therethrough of of the terminal strips which are disposed side-by-side in a row in each single stage. In the right-hand lug portion 5a of the base plate 5, there is formed a slit 6b having a size sufficient for receiving a terminal strip 2a therethrough. This slit 6b has vertical opposite end edges and is positioned on the extension of the elongated slit 5c in such a way that the left-hand vertical wall of this slit 6b is spaced at a distance 1 (shown in FIG. 4) from the right-hand vertical end wall of the elongated slit 5c. Said distance t represents the interval between the opposing edges of any two terminal strips 20 and 2a which are arranged in side-by-side relationship in a single stage. Another slit 6a for the passage therethrough of a terminal strip is formed on the same extension as that on which is located the slit 6b so that this slit 6a is positioned on the outer side of the slit 6b at the same distance r from the right-hand end edge of the slit 6b. In the right-hand lug portion 5a and exactly one stage above that of the slits 6a and 6b, there are formed a horizontal row of two equal slits 7a and 7b for the passage therethrough of two terminal strips contained in the adjacent upper stage relative to that for the slits 6a and 6b. In the same way, in the left-hand lug portion 5b are formed a slit a for the passage therethrough of a terminal strip 2a. This slit 6a is positioned at the distance t from the left-hand vertical end wall of the elongated slit 5c on the extension of the latter, said distance 1 representing the interval between the horizontally arranged two terminal strips as in the case of the slit 6a. Another slit 6b is formed on the outer side of the slit 6a in the lug portion 5b at the same distance r from the left end of the slit 6a, so as to lie on the extension of the elongated slit 50. One stage below the slits 6a and 6b, are formed two slits 7a and 7b for the passage of the horizontally arranged two terminal strips contained in the adjacent lower stage.

Between the slits 6a and 7a,, slits 6b and 7b and between the slits 7a and 6a,, slits 7b and 6b, on the surface of the base plate 5 having the aforesaid structure, wirings are provided by the application thereto of copper foils having an appropriate breadth by relying on the known techniques of forming printed circuits. It should be noted that the opposite terminals of the respective wirings are each formed into an enlarged portion covering the peripheral regions surrounding the open edges of each slit. The peripheral regions of the slits 7a and 7b located on the right upper stage of the base plate 5 are connected to the peripheral regions of the slits 6a, and 6b,, respectively, which are located on the intermediate stage on the left end portion of the base plate by two wirings 8 and 9 which run longitudinally on the surfaces of the base plate in the region above the elongated slit 5c at appropriately spaced relationship relative to each other. Also, the peripheral regions of the slits 6a and 6b located on the intermediate stage on the right-hand end portion of the base plate are connected to the slits 7a, and 7b,, respectively, which are located on the lower stage on the left end portion of the base plate by leading the wirings l0 and 11 so as to run longitudinally on the side below the elongated slit 50. Thus, an interconnecting device (intramanual coupler) is constructed.

This interconnecting device is attached to the switch assembly by applying the slits 7a, 7b and 6a and 6b which are formed in the right-hand end portion of the base plate 5 onto the terminal strips 20 which are contained in the first and second vertical rows of the upper and the intermediate horizontal stages, respectively, and also by applying the slits 6a,, 6b, and 7a,, 7b, which are formed in the left-hand end portion of the base plate onto the terminal strips 2a which are contained in the 13th and 14th vertical rows of the intermediate and the lower stages, respectively, as shown in FIG. 4. The manner of attachment of said interconnecting device is such that the third to 11th terminal strips contained in the upper stage are allowed to project along the upper passageway, i.e., along the longitudinal cutout edge of the base plate 5 and that the first to twelfth terminal strips contained in the lower stage are allowed to project along the lower passageway, i.e., along the lower longitudinal cutout edge of the base plate. Also, the third to 12th terminal strips contained in the intermediate stage are allowed to project through the elongated slit 50. Thus, the interconnecting device can be attached closely to the rear side of the switch box 1. After this interconnecting device is attached to the switch box 1 in the manner described, the regions of the respective wirings 8, 9, 10 and 11 surrounding the slits formed on the opposite end portions of the base plate 5 are soldered to their corresponding projecting terminal strips 2a. As a consequence, the two movable contacts (correspondting to C, and Cfl keys and fed with C and C tone signals) of 4-foot register contained in the upper stage are electrically connected to the two movable contacts (corresponding to C and C 3 keys and fed with C and C; tone signals) of 8-foot register contained in the intermediate stage. Also, the first two terminal strips (corresponding to C and C: keys and fed with C and C; tone signals) of the 8-foot register contained in the intermediate stage are connected to the two terminal strips (corresponding to C and C" keys and fed with C and C, tone signals) of 16-foot register contained in the lower stage, respectively.

Next, as shown by the chain lines in FIG. 4, the slits formed in the right-hand end portion of another similar interconnecting device are mounted on the third and fourth projecting terminal strips contained in the upper and the intermediate stages and the slits in the left-hand end portion of the device are mounted on the 15th and 16th terminal strips contained in the intermediate and the lower stages. Thus, those terminal strips containedin the respective stages and dealing with the same tone pitch signals are electrically connected with each other. By the use of four similar interconnecting devices and by connecting, in the manner described, the terminal strips in the respective stages in succession to those dealing with the same tone pitch signals and contained in the respective adjacent stages, it will be understood that there can be established the interconnection between the terminal strips of the movable contacts in the respective stages and the terminal strips dealing with the same tone pitch signals and contained in their respective adjacent stages. Therefore, the lead wires extending from the tone source circuits may be connected to only those terminal strips of the movable contacts contained in the 16-foot register of the lowermost stage, those terminal strips contained in the 8-foot register to deal with the tone signals C#,, C, corresponding to the key names Ca C and those in the 4-foot register to deal with the tone signals c, C corresponding to the key names C# C whereupon, all of the terminal strips of the movable contacts of the 4-foot, 8- foot and l6-foot registers may now be supplied with signals having respective tone pitches designated for these respective terminal strips.

It should be noted that, in case the multistage switches are those, for example, four-stage switches, there are provided, in the right-hand end portion of the base plate, three side-by-side slits in three stages so that they may receive therethrough the desired three side-by-side terminal strips contained in each of the first (uppermost), the second and the third stages. In the same way as described, there are formed in the left-hand end portion of the base plate three side-by-side slits in three stages so that they may receive therethrough those side-byside terminal strips contained in the second, third and fourth stages. Furthermore, there are formed elongated slits in those regions of the base plate corresponding to the positions of two horizontal rows of terminal strips lying in the second and the third stages. Wirings are provided between the respective slits located in the right-hand portion of the base plate in the first, second and third stages and the respective slits located in the left-hand end portion of the base plate in the second, third and fourth stages by the use of conductors made of a material such as copper foils. Thus, a group of nine terminal strips in any one stage may be electrically connected simultaneously to the group of terminal strips of equal number and of the same tone pitches contained in their respective adjacent stages, and similar effect as that from the three stage device may be obtained.

As stated above, the present invention contemplates the provision of an improved interconnecting device for movable contacts of multi-stage keyboard switches in an electronic musical instrument. According to the present invention, there is formed an L-shaped cutout or a passageway in each of the opposite end portions of the base plate and also there may or may not be formed, depending on the requirement, an elongated slit or slits or passageways in that portion of the base plate having a reduced breadth between the cutouts formed on both longitudinal sides of the base plate. Thus, it is possible to positively attach this interconnecting device to the rear face of the switch box to interconnect the required terminal strips contained in two adjacent stages without causing the unnecessary projecting terminal strips contained in the uppermost, intermediate and lowermost stages to be blocked by the wall of the base plate since these terminal strips are freely passed through these passageways. Besides, in the left-hand lug portion of the base plate, there are formed slits or perforations for the passage therethrough of a plurality of terminal strips contained in the respective stages excluding the uppermost stage.

Whereas, in the right-hand lug portion, there are formed slits or perforations for the trespassing therethrough of an equal number of terminal strips contained in the respective stages excluding the lowermost stage. Between the slits of the respective stages located in the right-hand lug portion and the slits located of the respective adjacent stages located in the lefthand lug portion, there are provided Wirings of printed circuits to connect these two groups, respectively. Thus, it is possible to simultaneously connect the terminal strips of a plurality of movable contacts lying in any desired state to those terminal strips of an equal number of movable contacts contained in the adjacent stage and dealing with the same tone pitch signals. Thus, the present invention not only markedly simplities and facilitates the wiring operation but also eliminates the fear for the occurrence of erroneous connections. Furthermore, there was the problem, in the past, of cross-talking to occur in high-pitch zones owing to stray capacitances existing between the connections. According to the present invention, there takes place no such inconvenience because the respective Wirings or connections are spaced relative to each other.

I claim:

1. In a musical instrument of the type having a circuit for electronically producing a plurality of musical tones, switching apparatus having a plurality of electrically conductive contacts movable between deactuated and actuated positions, said plurality of movable contacts being arranged in a selected number of sets each of said sets corresponding to a different musical tone, each of said movable contacts of a said set having movable actuating means operably interconnecting each of said movable contacts in a said set so that movement of a said actuating means of a said set will effect substantially simultaneous movement of each of said contacts of a said set between said deactuated and actuated positions, a plurality of stationary conducting members each positioned so as to be engaged by a saidcontact when a said contact is moved to its said actuated position to produce a musical tone, the improvement which comprises an electrically insulated oblong base plate having end portions spaced apart a predetermined distance, each end portion having at least one row of spaced perforations, each end portion having the same number of perforations, each one of said perforations in said row of one end portion being electrically connected on the surface of said base plate with one of said perforations in a said row of the other of said end portions of said plate, each of said perforations being coated thereon with a conductive material and said conductive material of each of said perforations in a said row of one end portion engaging at least one of said movable contacts of one of said sets and said conductive material of each of said perforations in a said row of the other of said end portions engaging at least one of said movable contacts of another of said sets, said one and said another of said sets having a predetermined number of sets extending therebetween,

said base plate having a portion intermediate said end portions which is provided with passageways for receiving portions of the said sets of said movable contacts extending between said one and said another of said sets.

2. The apparatus as claimed in claim 1 wherein each one of said perforations in a said row of one end portion of said base plate is electrically connected on the surface of said base plate with one of said perforations in a said row of the other of said end portions of said plate by means of a conductor printed on the surface of said plate.

3. The apparatus as claimed in claim 1 in which said electrically insulated base plate is made with Mylar film. 

1. In a musical instrument of the type having a circuit for electronically producing a plurality of musical tones, switching apparatus having a plurality of electrically conductive contacts movable between deactuated and actuated positions, said plurality of movable contacts being arranged in a selected number of sets each of said sets corresponding to a different musical tone, each of said movable contacts of a said set having movable actuating means operably interconnecting each of said movable contacts in a said set so that movement of a said actuating means of a said set will effect substantially simultaneous movement of each of said contacts of a said set between said deactuated and actuated positions, a plurality of stationary conducting members each positioned so as to be engaged by a said contact when a said contact is moved to its said actuated position to produce a musical tone, the improvement which comprises an electrically insulated oblong base plate having end portions spaced apart a predetermined distance, each end portion having at least one row of spaced perforations, each end portion having the same number of perforations, each one of said perforations in said row of one end portion being electrically connected on the surface of said base plate with one of said perforations in a said row of the other of said end portions of said plate, each of said perforations being coated thereon with a conductive material and said conductive material of each of said perforations in a said row of one end portion engaging at least one of said movable contacts of one of said sets and said conductive material of each of said perforations in a said row of the other of said end portions engaging at least one of said movable contacts of another of said sets, said one and said another of said sets having a predetermined number of sets extending therebetween, said base plate having a portion intermediate said end portions which is provided with passageways for receiving portions of the said sets of said movable contacts extending between said one and said another of said sets.
 2. The apparatus as claimed in claim 1 wherein each one of said perforations in a said row of one end portion of said base plate is electrically connected on the surface of said base plate with one of said perforations in a said row of the other of said end portions of said plate by means of a conductor printed on the surface of said plate.
 3. The apparatus as claimed in claim 1 in which said electrically insulated base plate is made with Mylar film. 